Some people - particularly those using laptops - are encountering a problem where the screen brightness is too dim upon replacing Microsoft Windows with a Linux distribution as their main operating system. Although it affects all Linux distributions, the problem is actually due to the computer's BIOS settings. Certain hardware manufacturers have set it up so that if Windows is not detected running on their systems, the backlight is automatically disabled.Reactivating the Screen Backlight

This problem can be easily fixed by ensuring that the GRUB bootloader re-activates the backlight. To do this, first open up your terminal, and enter the following command: